IndustrialDriveDataDrive Board & Diagnostic Database
Diagnostic workflow

Unidrive Over Volts Braking and Regeneration Workflow

Entry symptom: Unidrive reports Over Volts during deceleration, lowering, stop, winder unwind or unstable closed-loop operation.

Safety controls before proceeding
  • Regenerative loads can move unexpectedly.
  • Brake resistor circuits can be hot and hazardous.
  • Verify DC bus discharge before access.

Investigation sequence

1

Confirm event condition

Record whether Over Volts occurs during decel/lowering or during unstable running.

2

Review ramp and load

Classify load inertia, hoist/winder condition and deceleration demand.

3

Inspect brake path

Check braking resistor, thermal protection, brake chopper and parameter context where fitted.

4

Check line and DC bus

Record input line and DC bus behaviour under qualified procedure.

5

Check feedback instability

For closed-loop machines, inspect whether encoder noise or hunting causes regenerative swings.

Stop conditions

  • Load cannot be made safe
  • Brake resistor overheats
  • Feedback instability is uncontrolled
  • DC bus discharge cannot be verified

Linked records

Over Volts
DC Bus Overvoltage Trip

The DC bus exceeded its trip boundary, commonly due to regenerative energy, ramp/brake configuration, braking resistor/chopper issues, line voltage or feedback-induced instability.

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Unidrive DC Bus and Braking Path

Routes Over Volts evidence through line voltage, DC bus, load regeneration, deceleration ramp, brake resistor, brake chopper and feedback-induced instability.

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